Bail way traffic controlling



BEST AV "LABLE COPY Sept. 16, 1947. J. J. VAN HORN V 1 RAILWAY TRAFFIC CONTROL-LING APPARATUS- 12 Sheets-Sheei '1 Original Filed Sept. 12, 1941 fi mmgr i r J UNNQ NE NN NNQRQM INVENTOR.

Jamar-J. Vanfla zz.

Sept. 16,1947. J. J. VAN HORN RAILWAY TRAFFIC couTnoLLinh APPARATUS 12 Sheets-Sheet 2 Original Filed Sept. 12 1941 HIS ATTORNEY. v

Sept. 16, 1941 J. J. VAN HORN RAIL-WAY TRAFFIC CONTROLLING APPARATUS Original Filed Sept. 12, 1941 l2 Sheets-Sheet 5 n m M H T m N H 0 m% r N T I M e 1 Z H J Y ,B U w o U n m m m L m gum L am a T whm n QQDRRJ hwmmw i n Y I mm fi NNN .fififikm whgw. NbEwm b EN m hwwm .J. J. VAN HORN RAILWAY TRAFFIC CONTROLLING APPARATUS Sept. 16, 1947.

Original Filed Sept. 12, 1941 12 Sheets-Sheet 4 INVENTOR- Janzeuhi VJDHOPH.

' H125 ATTORNEY.

Qwm fi 12 Sheets-Sheet 5 J RR J. J. VAN HORN RAILWAY TRAFFIC CONTROLLING APPARATUS I Original Filed Sept. 12; 1941 N m Av Qua Nmsw wmwwm 33% $0 @SQQ Sept. 16, 1947.

J. J. VAN HORN RAILWAY TRAFFIC CONTROLLING APPARATUS Sept. 16, 1947.

12 Sheets-Sheet e Origins-[Filed Sept. 12, 1941 EQ Es S Sc INVENTOR. VZznHoPn.

HIS Ammvz'r J. J. VAN HORN RAI L WAY TRAFFIC CONTROLLING APPARATUS Sept. 16, 1947.

Original Filed Sept 12, 1941 12 Sheets-Sheet 'T w; 7% i H ml mwmsm AR g h J \EENQN g Q r. .i 5 N. MN L v ESQ Nam 5% 5% @ES H 5% a N F EENQ {MW WM m Emu 0 Q A V m HQ 58% 1 Y Egg E E SE .Ewm w H Sept. 16, 1947.

J. J. VAN HORN KAI LWAY TRAFFIC CONTROLLING APPARATUS Original Filed Sept. 12, 1941 12 Sheets-Sheet N M R m HIS ATTORNEY I v Q 5 QG QQ Q r N \S QSQQ m f v Q SKQ A WQN 8 b \MQBN MW NN \W w wm w l Sept. 16, 1947.

J. J. VAN HORN RAILWAY TRAFFIC CONTROLLING APPARATUS Original Filed Sept. 12, 1941 l2 Sheets-Sheet 9 I J. J. VAN HORN RAILWAY TRAFFIC CONTROLLING APPARATUS Sept. 16, 1947.

Original Filed Sept. 12, 1941 I2 Sheets-Sheet l0 Ri s ' VENTOR MS ATTORNEY m m g 3% TS Q NNN L NNNQ N wvmk b mmww ww REE BSNN \swkmw NMWNW. W 5% $5 Spt. '16, 1947.

J. J. VAN HORN RAILWAY; TR AFFIC CONTROLLING APPARATUS Original Filed Sept. 12, 1941 12 Sheets-Sheet 11 b INVENTOR Jame mzHorn HLS' ATTORNEY J. J. VAN HORN RAILWAY TRAFFIC CONTROL-LING APPARATUS Sept.'16, 1947.

' Original Filed Sept. 12, 1941 12 Sheets-Sheet 12 SQwMm INVENTOR Jame azzHapn HIS ATTORNEY jLJ NKRQ Q P n I w: R w? Reissuecl Sept. 16, 1947 RAILWAY TRAFFIC CONTROLLING APPARATUS James J. Van Horn, Pittsburgh, Pa., assignor to The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania Original No. 2,344,573, dated March 21, 1944,

Serial No. 410,504, September 12, 1941. Application for reissue January 11, 1945, Serial No.

40 Claims.

My invention relates to railway traffic controlling apparatus and is directed more particularly to the control of traffic in a single track twoirection system wherein centralized traflic coniol or other suitable manual control is used for p :stablishing the traffic direction. A distinguish- .ng feature of my system is that it employs noranally deenergized track circuits and dispenses with all control line wires except the coded C. T. C. line circuit, if C. T. C. control is used.

One object of my invention is to provide a normally deenergized track circuit system of signal- Eng for traffic moving in either direction on a .ingle track, without employing the usual control ine wires. Another object of my invention is to establish the desired trafiic direction by means at the control office, the checking and safety features of the system bein brought into play automatically as a result of operation of such means. A further object of my invention is to provide certain inter-controls on the C. T. C. machine, if used, to prevent interference with the estab-' lished trafiic direction when an entrance signal is at proceed or the section is occupied by a train. A still further object of my invention is to provide for the proper control of highway crossing signals and electric switch locks in a normally de-energized, non-line-wire system of the character herein disclosed... An additional object of m invention is to use but one set of code responsive apparatus for controlling both signals at intermediate locations. A further object of my invention is to provide a block indication for certain track circuits by polarizing the code effective therein. Other objects, purposes, and characteristic features of my invention will be apparent from the description which follows.

I accomplish the foregoing objects by: applying a rail current code at the new eXit end of the stretch and cascading this code progressively over the track circuit sections to the new entrance end to thereby check unoccupancy of the stretch and obtain proper restrictive indications of the opposing signals as well as permissive indications of the signals for the new direction; using properly controlled stick repeater relays of the trafiic lever or other trafiic designating means in the control machine to prevent interference with the established trafiic direction and to permit following moves; using the code checking relay (FSA) for directional control when the stretch is unoccupied and using the eastbound stick relay (ES) and the westbound stick relay (WS) for this directional control when the stretch is occupied; using the approach relay (AR) for the control of the directional stick relays (ES and WS); employing an additional rail current of a slow code for highway crossing control purposes in conjunction with the normally deenergized track circuits of my invention; and employing polarized coded track circuits for switch lock control without line wires, and feeding coded energy from both ends of the section toward the electric switch lock to indicate that the track sections on each side of the lock are unoccupied and that, if occupied, the train is movin away from the lock.

The present invention is an improvement on the invention disclosed in the United States patent application Serial No. 403,502 filed on July 22, 1941, b Ralph R. Kemmerer for Railway trailic controlling apparatus, now Patent No. 2,316,961 issued April 20, 1943.

I shall describe several forms of apparatus embodying my invention, and shall then point out the novel features thereof in claims.

In the accompanying drawings, Figs. 1a to 12 taken together, with Fig. Id at the left, are 2. diagrammatic view showing one embodiment of my invention as applied to a stretch of single track railway extending between the passing sidings at the two ends of the stretch. Figs. lba and led are diagrammatic views showing Figs, 1b and 12 before amendment. Figs. 2a and 2b taken together, with Fig. 2a at the left, are a diagrammatic view showing myinvention applied to a highway crossing location within a stretch of single track such as shown in Fig. 1. Figs. 3a, 3b, and 3c taken together, with Fig. 3a at the left, are a diagrammatic view showing my invention applied to the control of electric switch locks associated with the single track stretch. Fig. 4 shows a modified form of a portion of the apparatus of Fig. 3, also embodying my invention. Fig. 4a is an explanatory track diagram for Fig. 4. Figs. 5a and 5b are modified forms of certain portions of the apparatus shown in Figs. 1a and 1e, respectively, and also embodying my invention.

Similar reference characters refer to similar parts in each of the several views.

The circuits and apparatus shown in the accompanying drawings, but not shown in the drawings of the original patent, illustrate one form of subject matter described and claimed broadly in the original patent, and this applicant does not assert any claim to novelt in the specific arrangement of apparatus shown except insofar as claimed in the original patent.

Referring first to Figs. la to 1e, inclusive, the

stretch of track between the passing sidings PSI and PS2 is divided by the usual insulated rail joints at locations E, F, G, H, I, J, and K, to form a number of track circuit sections. Each of these track'sections is identified by the reference character T with a distinguishing prefix which also identifies the apparatus associated with that section or location. The signals which govern traffic movements through the single track stretch are the head-block signals BR and ML at the respective ends of the stretch and the intermediate signals 1 and 8 at locations G and I. The cut section locations F, H, and J could like- Wise be provided with signals, if desired, by adding similar apparatus to that shown at the intermediate signal locations.

Each section of the single track stretch is, in reality, provided with two track circuits, one eastbound and one westbound, each of which includes a code following track relay TR at one end and a source of direct current track circuit energy,

conveniently shown as a battery, at the other I end; This current is properly coded under the influence of traflic conditions, or as initiated by the operator at the central control location shown diagrammatically as the control office in Fig. la. Depending upon the direction of trailic movement, only one or the other track circuit is effective at any one time as will become clear hereinafter. The control relays involved in an eastbound move generally carry the prefix E or R (for right-hand) and those which control westbound moves include the prefix W or L (for lefthand) in order to make the disclosure more readily'understandable.

For simplicity, I make use of but two codes, these comprising direct current periodically int'errupted at the rate of 75 times per minute for approac and 180 times per minute for clear signal indications. The coding is accomplished by means of suitable code transmitters 750T and ISOC'I which are well known. It is understood that for cab signaling purposes, alternating current coded over the contacts of these code transmitters couldbe superimposed on the direct current. track circuits but I have not shown this added complication since it does not involve my invention. Certain of the track circuits are polarized and employ polarized track relays as a means for providing anindication by means of a block light on the track model as to-the location of a train within the single track stretch. This feature will be described more fully hereinafter. Directional stick relays are used, for permitting following moves to be made without any further action being required on the part of the operator.

The relays BLFSR (Fig. 1a) and BRFSR (Fig. 1e) adjacent the two ends of the stretch are manually controlled trafiic direction selecting relays which govern the direction of traflic'movement through the stretch. The communication system by means of which the operator at the C. T. C. machine or control oflice may govern these re lays may be of any suitable type, but preferably it is of the selective or code type in which communication is established intermittently by means of. impulse codes transmitted over a single pair of line wires to the desired control location or fieldstation. The details of such a communication system do not enter actively into the present invention audit is deemed sufiicient for an understanding of the present invention topoint out that the trafiic direction from right to left Q1 westbound is established by moving the lever 8 in the control office (Fig. 1a) to the left-hand or L position so as to energize the traific relay BLFSR at the field station at the left-hand end of the stretch (location E), and that the trafiic direction from left to right or eastbound is established by moving the lever B to the right-hand or R position so as to energize the trafiic relay 'HR'FSR at the other end of the stretch (location K). It is understood that the communication system is also used to provide an indication of traflic and apparatus conditions within the stretch, as well as to prevent interference with the established traffic direction except under proper conditions as will be pointed out hereinafter. It may also be used to govern the traffic leaving the single track stretch at either end by controlling the signals and switches at such ends. One form of communication system suitable for use in my system is that shown in Letters Patent of the United States No. 2,229,249 granted to L. V. Lewis on January 21, 1941, for Remote control system, and the general designation of the relays comprising the C. T. C. portion of my system corresponds with that used in this patent. In order further to simplify the disclosure, I have used the same reference numbers as in the Lewis patent to designate corresponding terminals or wires of the field station code units at the two ends of the stretch, these wires serving to transmit analogous control or indication functions.

The C. T. C. equipment at the office includes a control machine having a panel on which is mounted a miniature diagram of the controlled track stretch together with the indication lamps and the traflic and signal levers as shown in Fig. 1a.

The signal levers BSIG and I OSIG are threeposition levers of usual construction, and the traffie lever B is of the three-position push-turn type such as is shown in Letters Patent of the United States No. 2,289,736, granted July 14, 1942. to Clarence S. Snavely and Regis H. Zetwo for Circuit controllers.

It is to be understood that an installation may be made up of a number of unit portions gen erally similar to the one shown in the drawings, but, as the invention may be fully understood from one such portion, only one has been illustrated in the drawings.

I shall now describe the operation of the apparatus ofmy invention in detail, first assuming that all of the track apparatus (except the code transmitters) is deenergized, and that the operator moves the traffic lever 8 to its left-hand or L position.

The contact SK (Fig. 1b) is closed during turning movement ofthe lever B and when the, lever reaches its position L energy is supplied tothe starting relay 23531 to pick up the contacts of this relay before the operators hand'is removed from the lever and contact SK opens. When relay 235 ST picks up, it establishes a stick circuit for itself to keep its contacts, picked up until a control code is sent to the associated field station, as explained in the above-identified patent to L. V. Lewis. 1

In addition, on movement of lever 8 to its position L energy is supplied over back contact (51 of relay 8R1? to relay BLP and its contacts pick up with the result that energy is supplied to a terminal 81. over front contact I3 of relay BLP when contact M of selector relay 2355 is pi k up.

As explained in the. Lewis'patent referred to above, each control code includes a distinctive code call by means of which a selector relay 235s or 2313, not shown, at the office and a similar relay, not shown, at one field station only is energized to effect temporary establishment of seven communication channels between the oflice and a station. The different stations have different code calls, consequently, the selector relays for different stations are not energized at the same time and the same channels provide communication at different times with all of the stations.

Accordingly, when the control code is transmitted to the field station 235 at the left-hand or west end of the single track stretch, contacts l3 and I4 of relays 8LP and 235s are closed and energy is supplied to terminal 81 at the office so that the field station equipment causes energy to be supplied from the corresponding terminal over back contact [6 of relay BRHSR to relay SLFSR and its contacts pick up, While the relay establishes a stick circuit for itself through terminal 88 of the field station unit to'keep the relay contacts picked up until, as explained in the Lewis patent, a control code is sent to this field station at a time when energy is not supplied to terminal 81 at the office.

The energization of relay BLFSR completes a circuit which energizes the code repeating relay BRTCTM on code to thereby transmit a corresponding code to the track section BRT. If the home relay SLAI-IR for signal ELA is deenergized, so that back contact 23 is closed, as shown, 75 code will be transmitted to condition signal IL at location G to display an approach indication. If, however, signal HLA is at approach or clear, then relay BLAHR will be energized so that 180 code will be supplied over contact 23, now closed in its up position. As shown, signal GLA is at stop so that the coding circuit for relay SRTCTM may be traced from the code transmitter wire 1513 which is one terminal of the 75 code source, back contact 23 of relay GLAHR, front contacts 24, 25, and 26 of relays 5TH, BRKM, and BLFSR (now'up) back contacts 21 and 23 of relays BRSR and 8RFR, and the winding of relay GRTCTM, to the other terminal C of the source. Contact 24 of relay 5TB. checks that an eastbound move has not been started past signal ER, and contact 25 of relay BRKM checks that the opposing signals ERA and BBC are at stop. The relay GRKM is controlled in substan tially the same manner as the relay IULKM at the opposite end of the stretch. Since relay BLAHR is well known, the specific control circuits for this relay is not shown in detail, it being sufficient to associate the relay with signal 6LA. Back contacts 21 and 28 of relays BRSR and BRFR, respectively, check that trailic has not been established for an eastbound move, as will be apparent hereinafter. Accordingly, with the apparatus in the condition illustrated, 75 code is being supplied to the section GRT from the track battery TB over the front point of coding contact 29 of relay ERTCTM.

The 75 code is received at location F by the westbound code following track relay GRWTR, over the back point of contact 30 of the eastbound track relay GRETR, and is relayed into the cut section EART over the coding contact 3| of relay ERWTR. This contact supplies a current impulse from the track battery TB over an obvious circuit each time that its front point closes. The '75 code is received by relay 'IWTR at location G, over the back point of contact 32 of relay 'IWCTM which results in the energization of relay 'IWTFSA which is slow acting by virtue of the resistor snub 33 and therefore retains its picked-up position while relay IWTR is coding. The energization of relay 'IWTFSA closes an obvious circuit over its front contact 35 and front contact 34 of relay 'IWTR for the code repeater relay TM which follows the code and controls a set of decoding apparatus common to both sections BART and IRT. Relay TM itself is also common to both these sections and when tralfic is eastbound, this relay is picked up over frontcontacts of the corresponding eastbound relays TETR and TETFSA and the back point of contact 35 of relay IWTFSA.

When relay TWFSA picks up, its contact 230 interrupts one circuit for lighting the marker and stop indication lamps of signal 1L and establishes the circuit controlled by contact 23l of relay II-IR and by contact 232 of relay IDR for causing the signal IL, when relay 'IRH is picked up, to display either its caution or its clear indication according as relay IDE is released or picked up.

Relay TM Will follow the code supplied by the TWTR relay (which in this case is 75 code) and in so doing will energize the slow pick-up, slow release relay 'IHR from the decodingtransformer IDT over the rectifying contact 36 of relay TM in the usual and well-known manner.

The transformer IDT is energized over the coding contact 31 of relay TM and this circuit also includes the front point of contact 38 of relay 'IWTFSA and the back point of contact 39 of relay TETFSA. Should relay TM be following the code instead of 75, then the decoding relay 'IDR which responds selectively to 180 code only, because of the presence of the resonant decoding unit IBBDU, will be energized in addition to relay IHR. Since relays 'IWTFSA and THE are both energized, a 180 code circuit is completed forthe code following relay IRECTM over the coding contact 4!) of code transmitter IBBCT and front points of contacts 41 and 42 of relays 'IWTFSA and THE, respectively, whereupon relay IRECTM will supply 180 code from battery TB over the front point of its coding contact 43 to the section IRT.

A portion of the energy supplied from battery TB to the rails of section 'IRT is supplied over a circuit including in series therewith a winding of the code following approach relay TWAR. As explained in Letters Patent of the United States No. 2,176,605 issued October 17, 1939, to Herman G. Blosser, the various parts of the equipment are arranged and proportioned so that when section IR'I is not occupied too little energy is supplied through the winding of relay IWAR to pick up the relay contact I62 so that it.

remains released and interrupts the pick-up circult of relay IWS. The various parts of the equipment are also arranged and proportionedl so that when a westbound train advances a pre-- determined distance in section 'IRT the shuntling effect of the train increases the energy supplied, through the relay 'IWAR sufiiciently to cause contact I62 of relay 'IWAR to be picked up each time an impulse of coded energy is supplied to. the rails of section 'IRT.

At the cut section location H, the 180 code will be received by relay IRWTR and re-transmitted or cascaded into section TART over the front point of coding contact 44 of this relay. This code will be received at signal location I in the same manner as described for the signal location G at hi desc pti n; neednetbeerepeat d With relaysv W T ;FS A; andJI-IR; both; energized;

llRT. From this section thecode. willbe re:

peated into section IOLTby, polar relay. 8RWTR (which-is connected in parallel with the polarized track relay BRWTRA) as hereinafter explained. Relays ISLTRA and IDLTRat location Klwillireceive the 180 code and will make it possible, for the operator to clear'the headlocksignal, IDL so as to permit a westbound; train .toenter thesingle track stretch.

Referring again to location I,- it:w;.ill be noted.

that the code supplied to section BRT is polarized and is of one polarity when the 180 code decoding relay BDR is energized so that thefront point of contact is closed; but is of the other polarity when relay 3DR is deenergizedand the back point of contact 48 is closed. Contact," selects either battery TBI or TB 2,-as1the, supply battery for the track code and since these batteries are oppositely poled, polarized track circuit operation is obtained. The reason for polarizing the block I-K is to provide a proper blockindication on the track model, which feature willbe described more full hereinafter. For the present, itwill be sufficient to state that the codefollowing biased polartrackrelay IBLTRA at location K is energized in parallel with the non-biased polarized code followingrelay lflL-TRA: and is checked over the polar contacts 49 and 50 oftthe latter relay, as explained in Letters Patentiof. the United States No. 2,250,214, issued July 22, 1941, to Harry E, Ashworth, to insure that the latter has responded properly to the; polarized track circuit code. The track relays of my system such as fiRWTR, TWTR, IRWTR, etc., are preferably of the biased polar ty e which means that these relays will respond only to current of the proper polarity. Current of the other polarity Will merely hold the contacts of theserelays more strongly in their released position. The nonbiased polarized track relays such as GRWI'RA and I lLTRA respond selectively to current of either polarity and their contacts remain in the position to which they were last operated.

The energy supplied from batteries TBI. and T132 to the rails of section BRTis supplied over circuits each of which includes in series therewith a winding of approach relay ,-8WAR. .which.

functions in the manner explainedin detail above in connection with relay lWAR. The relay BWAR is of the biased polar-type the contact of which picks up only when energy flows through the relay windings in a selected direction; The circuits of the relay windings and of the batteries TBI and T32 are arranged so that the energy supplied from each ofthebatteries flows through.-

the relay windingdn the proper direction to pick up the relay contact.

Returning again to location K; the coding ac-' tion of relay I BLTR, will energize the decoding transformer DT at l80-code over the coding contact so that both relays lllLDR and- BLFR will become energized. Relay GLFR. is the usual code detecting relay which remains energized on impulses of either '75 or 180 code. With relay BLFR. energized and polarized relayv IIILTRA- occupying its normal position as shown,.a.circuit will be completed to terminal SIAM the field station 7 unit over front contact 52.0f relay-BLFR, Wire 53, and the normal polar contact 54.;ofgrelay:

lllLTRA, so as to provide the-operator-with= an unoccupied westbound block. indication. on the track model. The energization of relayv BLFR.

. 56:.and ,Wires.5'l.and .5.8. to provide an indication atthe control office-that traflic is established for a westbound move.

As explainedin the. above-identified patent to L V-Lewis, the equipment at each ,field station includes a starting relay, not shown, which is energized and initiates transmission of an indicationcode from-thatfield station to theofiice, whenever there is a changein the position of any of the indicating relays-which govern energization of the-indication channels and also in response to a received control code even if no such change occurs. Each code initiated at a, field station causes indication codes to be transmitted to the ofiice to cause indication relays governed from this station to assume energized or released positions in accordance with the condition of energization of the indication channels at the field station.

Accordingly, the indication code sent from station 231 to the ofiice after the supply of energy to terminals BS'and 9| A of this field station unit picks up relays 8LFK and BLBK (Fig. lb) and they establish stick circuits for themselves so that they remain picked up until an indication code is sent from the field station 231 to the when relay BLBK picks up, a circuit is established for the westbound block-lamp. Illumination ofthese lamps informs the operator that the waysideequipment'has prepared the stretch for'westbound'trafiic and that the block is unoccupied.

In addition whenrelay BLFK picks up, its contact l59-(Fig. lb) prepares a stick circuit for relay 8LP to prevent release of relay BLP when relayBLBK is released, that is, when the stretch is -occupied.-

The operator may now clear one'of the signals IOLA or HlLC, depending on the position of the switch 9; to permit a westbound train to enter thestretch. In orderto clear one of these signals the signal lever IUSIG, Fig: la, is moved to its left-hand position so that when selector relay 231s picks up energy is supplied to terminal 84 atthe ofiice. The starting button, not shown, for this station may now be pressed to causev aucontrol code to be sent to station 231 at the right-hand. or east end ofthe stretch with theresult that energy is supplied through terminal B4 of the fieldv station unit to relay IOLHSR and its contacts pick uptoestablish for the relay a stick circuit governed by relay IDRHSRI, track relay 9TB, and its slowireleaserepeater relay Q'IPBR.

When relay I OLHSR picks up, its contact 296 interrupts the circuit ofv relayBRFSRto insure front contact 204 .ofrelay 8LF'R, and contact 205 .torelaylflLAI-IR; or IOLCHR. The contact 205 is governed in accordance with the position of switch 9 so as to establish the circuit of relay IOLAHR when and only when the switch is in its normal position and to establish the circuit of relay Ill'LCI-IR when and only when the switch is in its reverse position. As shown in the drawings the switch 9 is in its normal position so contact 205 establishes the circuit of relay IULAHR, and its contact 201 interrupts the circuit governing the stop indication of signal IBLA and establishes the circuit for causing this signal to display its caution or its clear indication according as contact 298 of relay lOLDR is released or picked up.

In addition, when relay HlLAHR picks up, its

contact 210 interrupts the circuit of relay IBLGP and its contacts release so that contact 2| i interrupts the circuit of relay IHLKM and it releases to interrupt its stick circuit and its contact 2|! interrupts the circuit of code transmitting relay IIJLTCTM to prevent supply of coded energy to the east end of the stretch after clearin of the signal authorizing entrance of a westbound train into the stretch.

In addition, on release of relay lilLKM, its contact 222 permits energy to be supplied to time element relay IOTER and thus permit relay IELKM to be picked up after a time interval in the event that signal lllLA or IBLB is put to stop manually,

On release of relay IEILGP its contact 2! connects the battery to terminal 92 of the C. 'I. C. system field station unit and an indication code is sent to the office to pick up relay IELHK, Fig. 1b, which may light a lamp, not shown, on the control panel, Fig. la, while contact l il of relay IULHK establishes a stick circuit for relay 8L1, Fig. 1b, to insure that there will be no interference with the established direction of traffic in the stretch after clearing of the signal governing entrance of westbound traffic into the stretch.

In the preceding description it has been assumed that the control code to pick up relay IULHSR and clear signal liiLA Was not transmitted until the track circuit apparatus had prepared the stretch for westbound traflic and indications thereof had been transmitted to the oflice. However, this sequence of operations is not essential and the code to pick up relay IBLHSR may be sent before the track circuit apparatus completes preparation of the stretch for westbound traffic so that the signal will clear as soon as the wayside equipment shows that this is proper and the signal clear and block indication codes will be transmitted to the office at the same time.

If the Single track stretch should include but one intermediate signal location (G), then the westbound block indication can be provided, as shown in Fig. b (Sh. 5) over a front contact of relay BLFR and a front contact of the 180 code detecting relay IOLDR. The eastbound block indication under this condition. Will similarly be provided, as shown in Fig. 5a (Sh. 1) over a front contact of relay BRFR and the 180 code detecting relay BRDR. In this arrangement, it is unnecessary to polarize the code in order to obtain a continuous block indication.

Having described the manner in which the apparatus is conditioned for a traiilc movement in the westbound direction over the stretch, I shall next trace the progress of a west bound train as it moves over the various sections.

When the train enters section ST, the track relay STR releases and interrupts the circuit of relay QTPBR. but relay STPBR is of a type the contacts of which are slow to release so they remain picked up for a substantial period subsequent to release of relay 9TB. On release of relay BTR its contact 2 l 5 interrupts the stick circuit of relay IBLHSR. and this relay releases to additionally interrupt the relay stick circuit. After a short time interval relay STPBR releases and its contact 2l6 shunts contact 2l5 of relay 9TB. in the circuit of relay IDLI-ISR to permit relay IIILHSR to be picked up during occupancy of section BT to clear a westbound signal for a following train.

On release of relay IULHSR its contact 203 interrupts the circuit of relay IDLAHR. and this relay releases so that its contact 201 interrupts the caution and clear control circuits of signal llILA and establishes the stop control circuit for this signal.

On release of relay IULAHR its contact 2H1 completes the circuit of relay IULGP and its contacts pick up so that contact 2l4 interrupts the connection to terminal 92 of the C. T. C. system field station unit with the result that subsequent indication codes sent to the oifice will report signals HEL at stop and release relay IULHK.

When relay HJLGP picks up, energy is supplied over its front contact 2 and back contact 220 of relay 9TB to relay IULKM and its contacts pick up so that contact 222 establishes a stick circuit for the relay to keep it energized after section ST is vacated and relay BTR picks up.

When relay IBLKM picks up, its front contact 2 I 2 in the circuit of relay IBLTCTM is closed but at this time the circuit of relay IBLTCTM is interrupted by a contact of relay 9TB, or by contact 13 of relay BLSR as explained below.

As the train enters section 9T, relay QTR will release and a circuit will be completed for the directional stick relay BLSR over the back contact 60 of relay STR and the front point of contact 61 of relay IULAHR which is the home relay for signal IBLA. If the train enters from the siding PS2, then the circuit for relay 8LSR will include the back point of contact 6| and the front point of contact 62 of the corresponding home relay HILCHR for signal IDLC. Once relay 8LSR picks up, it closes a stick circuit for itself over back contact 60 of relay 9TB and its own front contact 63. When the train enters section IULT, the code detecting relay BLFR will release, closing an auxiliary stick circuit for relay 8LSR over back contact 54 of relay BLFR, back points of contacts 62 and SI of relays IULCHR and IULAHR, and front contact 63 of relay 8LSR. This stick circuit does not include the back contact E0 of relay 9TB, so that when the train fully clears section ST and relay 9TB. picks up, the directional stick feature provided by relay BLSR will continue to be maintained. Furthermore, when. the train fully clears sections lllLT and SRT so that relay BLFR picks up on '75 code, an additional stick circuit for relay 8LSR will become eifective in order that this relay may remain energized during the whole time that the stretch is occupied. Consequently, the westbound traffic directional arrow on the track model will remain lighted. This additional stick circuit for relay 8LSR includes the front point of contact 64 of relay BLFR, reverse polar contact 65 of relay IDLTRA, and front contact 63 of relay 8LSR. Reverse polar contact 65 will close before relay BLFR picks up and will remain closed thereafter until the stretch is cleared, whereupon relay BDR at location I will become energized and will restore normal polarity code to block IK. Relay IGLTRA will then again become energized in the normal direction.

11 Referring to the C. T. C. system field station unit 23?, Fig. 1e, it will be seen that when relay BLFR is picked up energy is supplied over its front contact 56 to terminal 89 so that indication codes sent to the o'flice from this station pick up relay BLFK, Fig. 1b, to light the westbound trafiic direction lamp on the control panel, Fig. 1a, to show that westbound traific is established in the stretch. Energy is also supplied to terminal 89 of the C. T. C. system field station unit 231 when contact 56 of relay 8LFR is released provided contact 65 of relay BLSR is picked up. As explained above the relay SLSR is picked up as soon as a westbound train enters section 9T so that, when the train advances into section IBLT and causes relay BLFR to release, the supply of energ to terminal 89 of the field station unit is maintained by contact 66 of relay BLSR and indication codes sent to the oflice maintain relay BLFK picked up and thus maintain the westbound directional lamp on the cont-no]. panel lighted and to maintain the stick circuit for relay 8LP controlled by relay SLBK so that relay 8LP will remain. energized and maintain westbound traflic in the stretch during occupancy thereof.

Moreover, when section lIlLT is vacated and relay BLFR picks up, the supply of energy toterminal 89 of the field station unit is maintained so that the westbound trafiic direction lamp on the control panel of the C. T. C. machine remains lighted. When the stretch is vacated, this I light remains lighted until the operator sends a code to the west end of the stretch to release relay 8LFSR and out 01f the supply of coded energy to the rails of'the stretch and thereby release rela 8LFR while maintaining relay SLSR released.

When the train advances into section IULT and releases relay 8LFR, its. contact 204 additionally interrupts the circuit of relay IOLAI-IR to insure that this relay remains released and keeps signal IOLA at stop as long as section. IBLT is occupied.

When relay 8LF'R releases, its contact 52 interrupts the supply of energy to terminal 9IA of the field station unit 231 and the indication codes sent to the ofiice release relay SLBK, Fig. lb, so that it extinguishe-s the westbound block lamp on the panel of the control machine, Fig. 1a Extinguishment of this lamp at a time when the westbound trafiic direction lamp is lighted indicates to the operator that a. westbound train has entered the stretch.

In addition, release of relay BLBK at a time when relay BLFK is picked up completes for relay 8LP the stick circuit including its own front contact I58, front contact I69 of relay GLFK and back contact I59 of relay B-LBK to thereby prevent release of relay 8LP in the event lever B is moved away from its position L. Accordingly, after the stretch has been prepared for westbound trafiic and a westbound train enters the stretch, the relay 8LP is certain to remain picked up so that its contact l 3 maintains the supply of energy to terminal '87 to insure that control codes. sent to field station 235 keep relay BLFSR picked up to continue the supply of coded energy to the rails of the track stretch. This insures that the wayside equipment will maintain westbound traflic in the stretch after occupancy of the stretch and that the supply of coded energy to the exit end of the stretch cannot be discontinued with resultant display of stop indications by the signals at intermediate points in the track stretch in ad-- Vance of the train "in the stretch.

The westbound stick relay 8WS at location I is picked up over front contact M62 of the approach relay BWAR and front contacts 6'! and 68 of relays 8WTFSA and BHR, respectively, when the train approaches the signal 8L. When once picked up, relay BWS is retained energized during occupancy, over a stick circuit which includes its own front contact 65 and the back point of contact 68 of relay SHR. This stick circuit does not become operative, however, until the train passes signal 8L and shunts the track section IART so as to release relay BHR. With relay 8WS energized, relay 8E'GTM will respond to '75 code over a circuit which includes the code contact 76, front point of contact II of relay 8W3, and back point of contact 41 of relay BHR. Relay 8ECTM will transmit 75 code of reverse polarity over the front point of its contact 12 to the section I-K and the receipt of this code at location K will permit signal IiiLA or IOLC to provide an indication for a. following move through the stretch.

When the train enters section 'IART the track relay BWTR. remains released so that energy is no longer supplied to relays BWTFSA, TM, BHR and BDR. and these relays release with the result that contact 235 of relay 8WTFSA interrupts the circuits for signal 8L governed by relays 8BR and BDR and establishes a circuit to cause signal 8L to display its stop indication.

The energy of '75 code frequency and reverse polarity supplied over the rails of section IOLT when the train vacates section 8RT causes the contacts of relay IULTRA to move to their righthand or reverse position so that contact 54 interrupts the circuit leading to terminal BIA of the field station unit 231. The coded energy supplied over the section rails also operates relay IIlLTR to pick up relay BLFR so that its contact 56 establishes connection to terminal 89 of the field station 231. At this time contact 52 of relay 8LFR. is also picked up but energy is not supplied to terminal BIA of the field station unit since contact 54 of relay IOLTRA is in its reverse position. Accordingly, indication codes Sent to the office will maintain relay SLFK picked up to light the westbound direction lamp but will keep relay BLBK released to prevent lighting of the westbound block lamp, while relays BLFK and BLBK establish the stick circuit for relay 8LP and thus insure that westbound traffic will be maintained in the track stretch.

Also when relay BLFR. picks up, its contact 204 is closed to permit relay IOLAI-IR, or IULCI-IR to be energized if it is desired to authorize a. following train to enter the stretch.

When the train advances in section IRT within a predetermined distance of signal IL, the relay 'IWAR operates and establishes the pick-up circuit for relay 'IWS so that it picks up and prepares its stick circuit which iscompleted when the train enters section BART and causes relay IHR to release.

When the train advances into section BART, the track relay 'IWTR remains released and energy is no longer supplied to relays 'IWTFSA, TM, THR and IDE, and they release with the result that contact 230 of relay 'IWTFSA interrupts the circuits for signal IL governed by relays 'IHR and FDR and establishes a circuit for causing signal IL to display its stop indication.

As relay 'IWS is energized, energy of 75 code frequency is supplied over its front contact 236 and back contact 42 of relay IHR to relay IRECTM so that energy of 75 code frequency is supplied to the rails of section 'IRT and when the train vacates this section this energy operates relay IRWTR to cause coded energy to be supplied to the rails of section 'lAR-T. This energy operates relay BW'I'R to pick up relays BWTFSA and BHR but not relay BDR. When relay BHR picks up, its contact 68 interrupts the stick circuit for relay SWS and relay 'BWS releases since contact I62 o f relay SWAR. is released and interrupts the pick-up circuit for relay 8W8. In addition, when relay SHR. picks up, its contact 4'! changes the energy supplied to relay BECTM from 75 to 180 code frequency, but as relay 8DR remains released the coded energy supplied to the rails of section BRT continues to be of reverse polarity, and energy of 180 code frequency and-reverse polarity is supplied to the rails of section IOLT.

When relays BW'ISFA and SHR. pick up, the signal 81. is caused to display its caution indication.

The energy of 180 code frequency and reverse polarity supplied to the rails of section "1LT holds the contacts of relay lElL'IRA in their right-hand or reverse position so that contact 54 interrupts the circuit leading to terminal 91A of the C. T. C. system field station unit 231 to cause indication codes sent to the office to maintain relay BLBK released and keep the westbound block lamp dark to indicate that the block is occupied, and to maintain the stick circuit for relay BLP and thus insure that westbound traffic will be maintained in the track stretch.

The energy of 180 code frequency supplied to the rails of section lULT operates track relay IELTR to hold relay aLFR. picked up and to pick up relay IEJLDR so that signal iilLA will display its clear indication if the operator decides to clear this signal to permit a following train to enter the stretch.

It will be noted that relay SWTFSA provides the directional control when the track section ahead of signal BL is unoccupied, and that relay 8WS retains the directional control when this section is occupied. With this arrangement, one TM relay, one decoding transformer DT, one DR relay (BBB), and one HR. reiay (SI-IR) are suilicient for the control of the two signals 8L and 8B. If the stretch contains but one set of intermediate signals between the two passing sidings, then it becomes unnecessary to polarize the track circuit code for proper block indication because the 18f) code decoding relay HJLDR will then indicate the unoccupied condition of the block when the track circuits are energized and traffic is established for the westward direction.

When the train vacates the stretch, energy of 75 code frequency supplied at the exit end of the stretch feeds over the rails of sections GET and BART and operates relay TWTR-to pick up relays 'IWTFSA and THE to release relay ?WS and change the energy supplied to section IRT from 75 to 130 code frequency.

When relays IWTFSA and IHR pick up, the signal 1L displays its caution indication instead of its stop indication.

On the supply of energy of .80 code frequency to section 'IRT, energy of this frequency is supplied to section TART with the result that relay ElDR is picked up and causes signal 8L to display its clear indication while energy of 180 code frequency of normal polarity is now supplied to the rails of sections 8RT and IULT. This energy causes the contacts of relay IBLTRA to move to their left-hand or normal position, while this energy operates relay IULTR to keep relay BLFR picked up and energy is supplied over front contact 52 of relay BLFR and normal polar contact 54- of relay IULTRA to terminal 9lA of the field station unit and energy is also supplied over front contact 56 of relay SLFR to terminal 89 of the field station unit. As energy is supplied to terminals 89 and 91A of the field station unit an indication code is sent to the office to keep relay SLFK picked up and to pick up relay BLBK so that the westbound traiiic direction lamp and the westbound block lamp are both lighted to inform the operator that the stretch has been vacated.

In addition, as relays SLFK and SLBK are both picked up the stick circuit controlled by these relays for relay 8LP is interrupted, but, if lever B is in its left-hand position, the relay 8LP will be maintained energized by current supplied over its pick-up circuit.

At location K, Fig. 1e, upon receipt of coded energy of normal polarity over the rails of section IOLT, contact 65 of relay lilLTRA moves to its left-hand or normal position and interrupts the stick circuit of relay SLSR and it releases.

If the operator does not wish to authorize another westbound train to enter the stretch and has not cleared one of the signals liiLA or lllLC, he may now restore the track circuit equipment to its normal deenergized condition by moving the lever 8 to its center position. During this movement of the lever the contact SK is closed to establish a circuit for relay 235ST to cause a control code to be sent to field station 235. In addition, on movement of lever B to its center position, a contact of the lever interrupts the pick-up circuit for relay 8LP and its contacts release, assuming that the block is unoccupied so that relay 8LBK interrupts one stick circuit for relay SIP, and assuming that signals IULA and IDLC are at stop so that relay IGLHK is released and its contact IEI interrupts the other stick circuit for relay 8LP. On release of relay 81.? its contact I58 interrupts the relay stick circuits while its contact l3 interrupts the circuit leading to terminal 81 so that the control code sent to the field station 235 causes release of relay SLFSR with the result that its contact 26 interrupts the circuit of relay BRTCTM and thus discontinues the supply of coded energy to the rails of the section BRT so that relay ERWTR ceases to supply coded energy to the rails of section BART and relay 'IWTR ceases to operate and relays 'IHR, 'IWTFSA and lDR, release. At this time relay IWS is released so that on release of relay 'IHR. the stick circuit for relay 'IWS is not established and relay 'iWS remains released.

On release of relay lWTFSA its contact 238 interrupt the circuits for signal 1L governed by relays II-IR and IDR and establishes a circuit to cause signal 1L to display its stop indication.

On release of relay lRH at a time when relay lWS is released contact 42 of relay 'IHR discontinues the supply of coded energy to relay 'IRECTM and it ceases to cause coded energy to be supplied to the rails of section lR'I' and relay TRWTR ceases to supply coded energy to the rails of section TART. Accordingly, relay BWTR remains released and relays 8WTFSA, BER and 8DR. release and put signal 8L to stop. At this time relay 8WS is released so that on release of relay 8HR. the stick circuit for relay 8W8 is not established and relay SWS remains released.

On release of relay SHR when relay BWS is released contact 41 of relay 8H3. discontinues the supply of coded energy to relay 8ECTM and thus cuts off the supply of coded energy to section 8RT and causes relay BRWTR to cease supplying coded energy to the rails or section IULT.

When the supply of coded energy to the rails of section IIILT is cut off, relay IDLTR remains released and relays 8LFR and IOLDR release. On release of relay BLFRits contacts 56 and 52 interrupt the supply of energy to terminals 89 and 91A, respectively, of the C. T. C. system field station unit 231. At this time, relay BLSR. is released so that on release of contact 55 of relay 8LFR energy is not supplied to terminal 89. As terminals 89 and 9 IA are deenergized the indication code sent to the office releases relays 8LFK and BLBK to extinguish the westbound trafiic lamp and the westbound block lamp on the panel of the C. T. C. machine to indicate to the operator that the wayside equipment has ceased to establish westbound trafiic in the stretch.

I shall now explain how traflic is set up for a move in the eastbound direction. Since relay HJLTCTM" at location K is controlled over the back contacts 12 and 13 of relays BLFR and 815R, respectively, it is not possible to energize this relay while traflic is established for a westbound move because one or the other of these relays will be energized, dependin upon whether the stretch is unoccupied or occupied.

The circuit of relay IOLTCTM also includes front contact 2|2 of relay IDLKM which is picked up only when the signals I DLA and IOLC' both display stop indications so relay IOLTCTM cannot be caused to supply coded energy to the rails of section IOLT if either of the signals [OLA or IDLC is displaying a permissive indication.

If, at a time when the stretch is prepared for westbound trafiic, but is'unoccupied and the signals lllLA and IOLC are at stop, the operator decides to establish eastbound traflic, he may do so by moving the lever B from its position L to its position R. On initial movement of the lever energy is supplied over contact SK and a contact-'14, of the lever to starting relay 235ST to cause a control code to be sent to field station 235, while on movement of the lever B to its position R and prior to release of the lever energy is supplied over contact SK and a, contact R of the lever to starting relay 231ST to cause a control code to be sent to field station 231.

On movement of the lever B away from its position L the pick-up circuit for relay 8LP is interrupted and the relay releases since it is assumed that signals IDLA and IULC are at stop so that relay IOLHK is released and interrupts one stick circuit for relay 8LP, and as it is further assumed that the stretch is unoccupied so relay BLBK is picked up and interrupts the other stick circuit for relay 8LP. Accordingly, relay 8LP releases and its contact [3 interrupts the circuit leading to terminal 8''! and the control code sent to station 235 releases relay 8LFSR to cut oil the supply of coded energy to the west end of the stretch and thereby deenergize the track circuit equipment throughout the stretch, as explained above, so that indication codes are sent to the oflice to release relays BLFK and BLBK and extinguish the trafi'ic and block lamps on the panel of the C. T. C. machine.

In addition, on release of relay 8LP energy is supplied over a contact R. of lever B and back contact 222 of relay 8LP to relay BRP and its contacts pick up SQ that contact 223, Fig. 1b, establishes the circuit for supplying energy to terminal 8110f the C. T. C. machine when relay 231s picks up. Accordingly, the control code sent tothe station 231 at this time picks up relay BRFSR. to cause coded energy to be supplied to relay l'llLTCTM when the track circuit apparatus governing westbound trafiic in the stretch ceases to function and relay BLFR releases to close its back contact 12.

If at the time the operator decides to prepare the stretch for eastbound trafiic the track circuit equipment is deenergized, the operation of the equipment to establish eastbound traffic is similar to that described above except that relay BLFR is released and coding operation of relay IBLTCTM begins as soon as relay 8LFSR. picks up.

In either case on coding operation of relay lllLTCTM, coded energy is supplied to the rails of section I 0LT with the result that the track circuit apparatus functions in substantially the same manner as explained above in connection with establishment of westbound traflic in the stretch, to cascade or repeat coded energy through successive track sections to the West or entrance end of the stretch to pick up relays 8RFR and SRDR.

When relay BRFR picks up, energy is supplied over its front contact 225 to terminal 89 of the C. T. C. field station unit 235 and over front contact 226 of relay 8RFR and normal polar contact BRTRA to terminal 9| A of the field station unit so that indication codes are sent to the office to pick up relays 8RFK and BRBK to light the eastbound trafiic and block lamps on the C. T. C. machine control panel.

After picking up of relays BRFR, and BRDR the signal 6RA or BBC may be cleared upon transmission of a C. T. C, control code to pick up relay BRHSR. The local circuits for controlling signals ERA and BBC are similar to'those illustrated for signals IOLA and I OLC and a detailed description of these circuits is unnecessary.

The operation of the equipment during movement of an eastbound train through the stretch and to effect deenergization of the equipment after such a train movement is similar to that already described in connection with westbound trafiic and a. detailed explanation of the opertion of the equipment at such times is unnecessary.

Referring for the moment to the selector relays 2358 and 231s (shown in Fig. 1b) which control the transmission of code for energizing the westbound and eastbound traflic direction control relays BLCFSR. and BRFSR at field stations 235 and 231, respectively, it will be noted that energization of terminal 81 which is essential for code transmission, as will be apparent from the Lewis patent referred to hereinbefore, will not occur unless the lever 8 has been operated to its left or right-hand position and the corresponding lever repeater relay 8LP or BRP is energized. The pick-up circuit for each lever repeater relay is checked over a back contact of the other lever repeater relay. Movement of lever 8 to the L position will pick up relay 8LP over the back contact I 51 of lever repeater relay 8RP. Once relay 8LP picks up, a stick circuit will be completed therefor over its front contact I58. This stick circuit can be maintained either over the L contact of the lever, or over an auxiliary circuit Which includes the back contact I59 of the block (unoccupied or occupied) indicator relay SLBK and the front contact I60 of the trafiic di- 

